New Study Suggests that Death Rates for Some Cardiac and Cancer Surgeries May Be Linked to Surgeons' Experience

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Seeking out surgeons who frequently perform certain cardiac or cancer-related operations may increase older patients' odds of surviving major surgery, according to a new study supported by the Agency for Healthcare Research and Quality. The study, "Surgeon Volume and Operative Mortality in the United States," is published in the November 27, 2003, issue of the New England Journal of Medicine.

Previous research has suggested that hospitals with high annual volumes of certain types of surgical procedures have lower death rates than do hospitals where the volume of such surgeries is low. However, few studies have closely examined why high-volume hospitals do better, and little is known about relationships between hospital volume and surgeon volume in relation to surgical patient death rates.

Researchers led by Dartmouth Medical School's John D. Birkmeyer, M.D., found that patients of high-volume surgeons had lower death rates for heart bypass surgery, carotid endarterectomy—an operation to prevent stroke—lung resection, and five other cardiovascular and cancer procedures than did patients whose surgeons performed these operations less frequently. The likelihood of operative death for low-volume surgeon's patients was 24 percent greater for lung resection—an operation in which part or all of a lung is removed—and nearly four times greater for pancreatic resection surgery as compared with patients of high-volume surgeons.

Surgeon volume accounted for much of the apparent effect of hospital volume, ranging from 100 percent for aortic valve replacement to 24 percent for lung cancer surgery.

"These findings bring us one step closer to better understanding why death rates for different operations often vary widely," said AHRQ Director Carolyn M. Clancy, M.D. "The results of this study will be of interest to hospital administrators, health plan leaders, purchasers, and consumers."

Tom Scully, administrator of the Centers for Medicare & Medicaid Services, agreed. "Giving consumers information is an important step to improve the quality of health care," he said. "As a result of these studies, our staff will work with the physician community to explore ways to move forward to use this information."

The study findings suggest that high-volume surgeons' patients had lower death rates even when operated on in low-volume hospitals, while the patients of low-volume surgeons had higher death rates regardless of where they had their surgery.

In the study, high-volume surgeons performed an average of more than 162 heart bypass operations a year, compared with fewer than 101 a year by low-volume surgeons, and over 40 carotid endarterectomy operations annually as opposed to the fewer than 18 performed by low-volume surgeons. High-volume surgeons also performed an average of more than 17 lung resections and more than four pancreatic resections annually, compared with fewer than seven and two, respectively, by low-volume surgeons.

The researchers defined surgical mortality as death during the procedure, before hospital discharge, or within 30 days of the operation. They adjusted their findings to take into account personal factors that could affect odds of surviving major surgery, such as patients' age, sex, race, average income, presence of other illnesses, and whether the surgery was done as an elective or emergency procedure.

Dr. Birkmeyer, who is an associate professor of surgery at Dartmouth Medical School and chief of surgery at Dartmouth-Hitchcock Medical Center, and his colleagues used information from the national Medicare claims database on nearly 475,000 patients who underwent one of eight cardiovascular procedures or cancer surgeries between 1998 and 1999.

In a separate study examining hospital volume, "Regionalizing High-Risk Surgery: How Far Would Patients Have to Travel?" in the November 26 issue of the Journal of the American Medical Association, Dr. Birkmeyer and fellow researchers analyzed how far Medicare patients would have to travel if they opted or were required to have specific operations on their esophagus or pancreas in high-volume hospitals.

Findings from this study suggest that requiring patients to undergo these high-risk procedures at hospitals with minimum volume standards (defined as hospitals where one or more pancreatectomies and two or more esophagectomies are performed annually) would affect about 15 percent of patients undergoing these surgeries and would add fewer than 30 minutes to most patients' travel time.

Requiring patients to be operated on at hospitals with very high volume standards (17 or more pancreatectomies and 20 or more esophagectomies annually) would affect about 80 percent of patients undergoing these surgeries. However, setting hospital volume standards at higher levels would come at the cost of greatly increasing many patients' travel time to get to the hospital, especially for those living in rural areas.

The simulated trial was based on Medicare claims for more than 15,000 patients who had either esophagectomy or pancreatic resection between 1994 and 1999. The analysis was supported by AHRQ and CMS.